Nickel-iron alloys adapted for springs in thermocompensated oscillating systems



Patented Apr. 5, 1949 NICKEL-IRON ALLOYS ADAPTED FOR SPRINGS IN THERMOCOMPENSATE OSCILLATING SYJTEMS Reinhard Straumann, Waldenbui'g, Canton of Bale-Campagne, Switzerland No Drawing. Application November 2, 1945, Serial No. 626,430. In Switzerland March 30, 1942 Section 1, 'Public'Law 690, August 8, 194.6

I i Patent expires March 30, 1962 This application is a plication of mycopending patent application Ser. No. 549,286, filed August 12,1944, now abandoned.

A nickel iron alloy for the springs of thermocompensated oscillating systems, for example balance springs for clocks and watches, is known which, by additions of beryllium, titanium and of metals of the chromium group exactly proportioned in relation to one another as well as to the nickel content yields a hard, highly elastic spring which has -a thermo-elastic coefficient which is zero, positive or negative according to the choice and, proportion of the additions and which can be 'fixed in shape in a satisfactory manner at the refining temperature.

Manufacturing experience with this alloy has shown that the Curie-point with +35 to 40 C. is somewhat low, the consequence of this being that springs made of this alloy will usually cause considerable secondary errors of oscillating systems controlled thereby. Recently, higher requirements have been imposed upon the temperature coefiicient of the oscillating system of watches in the sense that the range of temperature, in which the watch must run exactly, has been enlarged from to +30 C. to 0 up to +40 C. In this range enlarged up to +40 C. the detrimental secondary error will be even greater than in the range up to +30 C.

Tests have shown that with an addition of 02-03% carbon the above mentioned disadvantages can be eliminated without injuring the good qualities of the oscillating springs made of the above said alloy.

The addition of carbon in the appropriate proportion with regard to the addition of beryllium and titanium causes a dislocation of the Curie-point and consequently a displacement of the positively curved part of the temperature running curve up to higher temperatures, so that in the useful range this curve will be nearly rectilinear. Besides, the dependence of ,the therino-elastic ooefilcient on thefixing temperature will become yet smaller than it is in alloys known up to now,'.wherefrom it results that the straying effect of this ooefiicient of the spring manufactured in large quantities will be considerably reduced.

For alloys having an addition of carbon within the above given limits the Curie-point lies between +80' and +l00 C. Springs made of such alloys are somewhat sensitive to magnetic influences. Now it has been found that this magnetic sensitiveness can be reduced by reducing the content of carbon. With an addition of continuation-impart ap- '1 Claim. (01. -128) carbon amounting to only from 0.0 05-0.2% springs will be obtained which are not at all or very little sensitive to magnetic influences. The Curie-point of these alloys having a reduced addition of carbon lies between +40 and C. Thus it will be seen that an alloy having a higher addition of carbon will yield springs with a higher compensating range of temperature, but which are sensitive to magnetic influences, whilst by using an alloy containing a smaller addition of carbon springs will be obtained which are substantially non-sensitive to I magnetic influences, but having a lower compensating temperature range.

I In view of the foregoing the present invention relates to a spring of nickel iron alloy with a hardening addition of beryllium, especially for thermo-compensated oscillating systems, for instance of watches, this spring being characterized in that the alloy of which it is made contains 25-40% nickel, 0.52% beryllium, 23-12% of at least one metal of the chromium group (for instance chromium, molybdenum or tungsten), 0.5-2% titanium, 0.005-0.8% carbon, the remainder being substantially iron, whereby the proportions of the quantities of metals ar chosen so that besides the great hardness achieved and the low temperature coefiicient of the modulus of elasticity the temperature running curve of an oscillatingsystem controlled by such a spring will be practically rectilinear in the temperature range of 0 to +80 C. By using an alloy of the above said composition balance springs having the following advantages may be produced:

1. A nearly rectilinear form of the temperature running curve according to the percentage of carbon up to temperatures of +40", 50 or even 2, A low straying effect of the thermo-elastic coefficient of the springs manufactured in large quantities.

3. A fixing temperature still lower than for alloys known up to now.

The following nickel iron alloys for example yield springs which have the above advantages.

Emample'i W Per cent Ni 30-38 7' W 5-10. Be 0.5-2 Ti 0.5-2

C 0.005-0;8 Si-l-Mn 1 Remainder Fe.

Example 2 Per cent Ni 30-38 Mo 5-10 Be 0.5-2 Ti 0.5-2 C 0.005-0.8 Si+Mn 1 Remainder Fe.

Example 3 Per cent Ni 1 30-38 Cr Be 0.5-2 Ti 0.5-2 C 0.005-0.8 Si+Mn 1 Remainder Fe.

Example 4 Per cent in 30-38 a 5-10 fie 0.5-2 0.5-2' 0.2-0.8 +Mn 1 Remainder Fe Example 5 Per cent N 1 30-38 Mo 5-10 Be 0.5-2 0.5-2 0.2-0.8 n 1 Remainder Fe Example 6 Per cent Ni 30-38 or -9 Be 0.5-2 Ti 0.5-2 .c -1 0.2-0.8 SH-Mn 1 Remainder Fe Example 7 Per cent -Ni a 30-38 w i 540 Be 0.5-2 Ti 0.5-2 G 4:; 0.005-(12 Si+Mn -4 1 Remainder Fe.

Example 8 Per cent M -10 'B'e 0.5-2

0.5-2 C 0.005-0 2 Si-l-Mn 1 Remainder Fe Example 9 Per cent Ni 30-38 Qr 6-9 Be 0.5-2 n 0.5-2 C 0.005-0.2 Si-l-Mn 1 Reminder Fe.

Obviously, two or all three of the alloying metals of the group consisting of chromium, molybdenum and tungsten can also be present together or simultaneously in the alloy, always provided that their total content amounts to from 5 to 12% of the alloy, as can be seen from the following examples.

Example 10 Per cent Ni -38 Mo 2-4 W 3-5 Be 0.5-2 Ti 1 0.5-2 C 0005-08 Si+Mn 1 Remainder Fe.

Example 11 Per cent Ni 30-38 Gr 1-2 W 2.5-3.5 M0 2-3 Be 0.5-2 Ti 0.5-2 C 0.005-0.8 Si-l-Mn 1 Remainder Fe.

What I claim is:

A nickel-iron alloy, particularly useful for springs of thermo-compensated oscillating systems, the temperature running curves of which will thereby be rendered practically rectilinear in the temperature range of 0 to 50 C., said alloy containing Per cent Ni 25 to 40 13a 1 0.5 to 2 Ti 0.5 m2 0 0.2 to 0.8 Si-I-Mh 1 in addition to at least one of the metals of the group consisting of molybdenum, chromium and tungsten, the total content of the metals of the said group amounting to 5 to 12%, and the remainder of the alloy being iron.

REINHARD STRAUMANN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,072,489 Straumann Mar. 2, 1937 OTHER REFERENCES The Metal Iron, pages to 73; by Cleaves and Thompson. Published in 1935 by the McGraw- Hill Book Co., New York.

Making, Shaping and Treating of Steel, page 975; by Camp and Francis. Published in 1940 by the Carnegie-Illinois Steel Corporation, Pittsburgh, Pa. 

